The miniaturization of electronic components, for which a resolution down to the range of less than 1 μm is required, has been achieved substantially by photolithographic techniques. To give further smaller structures, miniaturization is being achieved by the progress of ArF lithography and ArF immersion lithography technologies. However, the size of such a small structure of about 32 nm or less approximates to the size of a resin used, and this causes problems such as line edge roughness to come to the surface. On the other hand, the increasingly high requirements with respect to resolution, wall slope, and aspect ratio (ratio of height to resolution) result in a cost explosion in the case of the apparatuses required for photolithographic structuring, such as masks, mask aligners, and steppers. In particular, owing to their price of several billion yen, modern steppers are a considerable cost factor in microchip production. Independently, there is an attempt to use short-wave radiation, such as electron beams and X-rays, for achieving higher resolution. However, this technique still has many problems from the viewpoint of productivity.
Nanoimprint techniques are expected as an alternative to these techniques. Among the nanoimprint techniques, those mainly known are a thermal nanoimprint technique, in which a thermoplastic resin is heated and softened, then a mold having a predetermined pattern is pressed thereagainst to form a pattern on the thermoplastic resin; and an ultraviolet nanoimprint technique (UV-nanoimprint technique), in which a photocurable compound is applied to a substrate, and, after the substrate and a mold are pressed against each other, the resin composition is cured in ultraviolet rays and becomes solid to give a pattern. Though both of them are excellent techniques, the UV-nanoimprint technique is expected to give a further higher throughput, because this technique employs light to cure the resin and thereby does not need a heating and cooling process in contrast to the thermal nanoimprint technique. In addition to this, the UV-nanoimprint technique has several key features as follows. Specifically, the UV-nanoimprint technique can easily and conveniently give a further higher registration, because it uses a transparent mold. In addition, the UV-nanoimprint technique uses a composition mainly containing liquid monomers in combination and can thereby form a pattern under a very low transfer pressure as compared to that in the thermal nanoimprint technique.
Patent Document 1 describes a nanoimprint process which is based on a thermoplastic deformation of a resist, applied to the whole surface of a substrate, by a relief present on a rigid stamp. Thermoplastics (poly(methyl methacrylate)s, PMMAs) are used as a resist for hot stamping. Owing to common thickness variations of about 100 nm over the total wafer surface, it is not possible to structure 6-, 8-, and 12-inch wafers in one step with a rigid stamp. Thus, a complicated “step and repeat” method would have to be used, which, however, is unsuitable owing to the reheating of already structured neighboring areas.
In Patent Documents 2, 3, and 4, a stamp is wet with a UV-curable resist (self-assembled monolayer, e.g. alkylsiloxane) and then pressed onto a smooth substrate. Analogously to a common stamp process, the structured resist material is formed when the stamp is raised from the substrate surface. The resist materials used exhibit sufficient wetting with respect to the substrate but are not suitable for a lift-off method, nor do they have sufficient etch resistance. The structure dimensions are in the region of 1 μm and are thus more than one order of magnitude too large.
Patent Document 5 reports another nanoimprint technique in which a fluorine-containing polymer is used to improve mold releasability (releasability from the mold). This technique, however, sacrifices adhesion to the substrate for the improvement in mold releasability and is thereby unsuitable for the formation of a satisfactory pattern, owing to the free-radical curing, non-solvent system employed as a reaction system. Especially when the nanoimprint technique is used as an alternate for photolithography, a smaller thickness of residual film is desired. However, when adopted to such use, the nanoimprint technique gives a film having insufficient adhesion to the substrate.
These processes and techniques are all unsuitable for achieving objects of the present invention as mentioned below.    Patent Document 1: U.S. Pat. No. 5,772,905    Patent Document 2: U.S. Pat. No. 5,900,160    Patent Document 3: U.S. Pat. No. 5,925,259    Patent Document 4: U.S. Pat. No. 5,817,242    Patent Document 5: Japanese Unexamined Patent Application Publication (JP-A) No. 2007-1250